AquaChem drop tester from WalMart. Just drained over half of pool to lower CYA and refilled before yesterdays thunder / lightning storm.
Todays numbers are a mix of remaining pool water, rain water, and refill water.
IG Fiberglass 6500gal Pool:
Chlorine over 5.0
Ph 7.6
CYA 55
Then another thunder / lightning storm arrived suddenly so I had to stop and go in. Spring time in NE Florida, gotta love it.
So I thought I would test house water from kitchen sink.

Chlorine: 4.5
Ph 7.8
TA 150
Hardness 400ppm
Did not test CYA as the solution is soooo $$$.